Actuating device for rock-drills



(No Model.) 3 Shets-Sheet 1,

J. DUNCAN. AGTUATING DEVICE FOR BOOK DRILLS.

No. 539,251. Patented May 14, 1895.

R N 5 g 10L 5 5 INVENTOR:

3 Sheets-Sheet 2.

(No Model.)

Patented May 14, 1895.

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' J. DUNCAN.

AGTUATING DEVICE FOR ROCK DRILLS.

NQ. 539,251. Patent-ed May 14,1895.

NITED STATE ATENT intros.

ACTU ATING DEVICE FOR ROCK-DRILLS.

SPECIFICATION forming part of Letters Patent No. 539,251, dated May 14,1895.

Application filed March 11, 1895.

To all whom it may concern;

Be it known that I, JOSEPH DUNCAN, of Lykens, in the State ofPennsylvania, have invented certain new and useful Improvements inActuating Devices for Rock-Drills, (he, whereof thefollowing is aspecification, reference being bad to the accompanying drawings.

In said drawings, Figure 1 represents a longitudinal central sectionthrough the cylinder and valve-chest ofthe drill, showing thedrill-piston and a portion of the drill-shank in elevation. Fig. 2 is atop or plan exterior View of the said cylinder and valve-chest. Fig. 3is a vertical transverse sectionon the line 3 3 of Fig. 1. Fig. 4 is afront end view of the cylinder, showing the drill-shank in transversesection. Fig. 5 is a rear view of said cylinder, showing certain of theinternal mechanism in dotted lines.

A indicates the actuating cylinder of the drill piston. The shank of thedrill is represented at B, and extends out through a stuffing box in thehead,a, at the front end of the cylinder, said stuffing box containingpacking rings, D, which are maintained in position by means of a coiledspring, (1. Said spring tends to force the packing rings toward theconverging front end, a, of the stuffing box and thus maintain aclosejoint about the shank, B.

The piston, C, may be formed integral with the shank, and consists of acylinder having packing rings, 0, c, and fitting snugly within theinterior of the cylinder, A. This piston is preferably provided with alongitudinal hole, extending inward from its rear end, and indicated bythe dotted lines at O, the inner surface of which is rifled or providedwith a thread of very steep pitch, to engage with the correspondinglythreaded portions of a rifle-bar, E, rotatably mounted in the cap, F, atthe rear end of the cylinder, and provided with a ratchet, e, andspring-pawl, e, which maintain said bar, E, against rotation in onedirection, while permitting it in the other. This device, which iscommon in this class of apparatus .to effect a slight rotary movement ofthe drill after each stroke, need not be further described, as it formsno part of my invention.

At each end of the cylinder is a gum ring,

' thereof at each end, as shown.

Serial No. 541,344.. (No model.)

The head, a, at the front end of the cylinder, and the cap, F, at therear end thereof, may be conveniently secured in position by means oflongitudinal bolts, F, F extending longitudinally with the cylinder oneach side thereof and passing through 1ugs,f,f, upon the cap, F, andsimilar lugs,f ,fupon the head, a. Said bolts are provided withv nuts, f,f ,f f whereby the proper tension may beproduced upon the bolts, F, F.

Upon the under side of the cylinder is preferably cast a longitudinalsleeve, A, to re-' ceive the usual hand feeding spindle to advance orwithdraw the drill and its cylinder, but which need not be described, asit forms no part of my invention. Upon the top of the cylinder, A, ismounted the valve chest, G, which may be approximately cylindrical inform, having two heads, g, g, secured in position by means of bolts andnuts, h, h, engaging through lugs formed upon the heads and end portionsof the valvechest body on each side, or maintained in position in anyconvenient manner. The interiorof said valve-chest is provided with atubular bushing, K, extending from end to end, as shown, but having anannular space between its exterior surface and the interior surface ofthe valve-chest, extending throughout the whole-of the length and nearlyall of the periphery thereof. Segmental ports, 71:, k, are formed in theupper portion of this bushing ata short distance from the ends thereof,and somewhat larger ports, Z, Z, are formed in the lower portion of thebushing, in correspondence with the inlet passages, L, L, extendingalong in the wall of the cylinder, A, and communicating with theinterior Said passages constitute the inlet ports of the cylinder, andwill hereinafter be so termed.

The central portion of the cavity within the cylinder, A, is providedwith a lateral off- O, 0, respectively, communicating with the annularspace between the bushing, K, and the inner wall of the chest. Theseinlets and the exhaust ports 3' ust referred to, are provided induplicate, in order to accommodate the drill to working in variouspositions, the opensnugly within the bushing, K, and of such length asthat when in one extreme position it shall close one port, as 7r,leaving the other port, as 7.3, fully open. In such position it. extendspartly over, but does not close, the port,l, which is below the port,is, and it ontirely opens the corresponding port, Z, which is below theport, 7s. The extreme positions of the valve, P, are defined by lugs,12,19, respectively, extending inward .to the proper distance from eachhead of the valve-chest.

The length of the piston, C, is such that when it is inone extremeposition, as for instance, at the rearend of the cylinder, there is afree-communication between the interior of the cylinder at the frontportion of the piston and the exhaust offset, M, and exhaust port, N,and vice versa.

The operation of the device is as follows: Assuming the parts to be inthe position shown in Fig. 1, compressed air or other fluid underpressure entering by the pipe, 0, and port, 0, will escape into theannular space between the bushing, K, and the inner surface of thevalve-chest, G, and will pass freely down through the port, Z, into andthrough the inlet port, L, at that end of the cylinder, thereby forcingthe piston forward. During a portion of the forward stroke of thepiston, the outlet through the offset, M, and exhaust port, N, is open,and the air from thefront of the piston is exhausted thereat; but afterthe front end of the piston passes the point, m, the remaining .air iscompressed during the continuation of the stroke, the compression takingplace in the front end of the cylinder,

A, the port, L, and the interior part of the.

bushing, K, behind the valve, P, whose end is at that momentabuttingagainst the projection, 1). hen this compression has reached a certaindegree of tension, it will shift the valve, P, to the other end of thevalve-chest,

thus cutting off further access of air through the port, 7c, and openingthe port, 7c, and consequently bringing the inlet port at that end ofthe cylinder into communication with the source of compressed air.Thereupon the return stroke of the piston, C, will occur and partialexhaustion and subsequent partial compression of the contents at :rearend of the cylinder will recur. When the necessary degree of tension hasbeen reached at this end, th e valve, P, will be shifted in a mannersimilar to that described, so as to again open communication with theinlet for compressed air-to the rear end of the cylinder and cut it 0%from the front end thereof. A reciprocab,

ing motion of practically any required speed and force may be thusobtained by proper regulation of the air blast entering at the in.- letpipe, 0.

The actuating device has been described in connection with a rock drill,but obviously could be utilized for other purposes where a reciprocatingmotionisdesired, and hence I do not limit my claim to this particularapplication thereof; nor do I deem it necessary to enlarge upon theobvious features of advantage which are embodied in my invention, beyondpointing out the great simplicity thereof, the small number of Workingparts, and the solidity of those parts which are most liable to accidentin devices of this character.

Having thus described my invention, I claim- 1. The combination with acylinder having inlet and exhaust ports,.substautially as set forth, ofa piston arranged in the described manner with reference-to said exhaustports; a valve-chest communicating with the inlet ports of the cylinderand provided with individual inlet ports near each end; a reciprocatingvalve arranged within said valve-chest and adapted in its extremepositions to entirely open one inlet port of the cylinder and the otherinlet port of the valve-chest, while entirely closing the other inletport of the valve-chest and partly closing the other inlet port of thecylinder, whereby a com munication between the interior of the valvechest and the interior of the cylinder, at each end thereof, at alltimes exists, but communication between the air or other inlet and theinterior of the valve-chest at either end thereof is alternatelycompletely out off and opened, substantially as set forth.

2. The combination of the cylinder having inlet ports communicating withthe respective ends thereof, and an exhaust offset and exhaust at itscentral portion; a valve-chest having a bushing forming an annular spacetherein, said bushing being provided with ports in correspondence withtheinlet ports of the cylinder and also with individual inlet ports neareach end of the valve-chest; a reciprocating valve arranged within saidbushing and adapted in one extreme position to entirely close one of theindividual inlet ports of the valve-chest while opening the other, andvice versa, but not closing the inlet ports of the cylinder, saidvalve-chest being provided with an air inlet communicating with saidannular space, substantially as set forth.

JOSEPH DUNCAN. lVitnesses:

H001) MCKAY, OTTO LONG.

